


Making Purple

by I_Write_Sans_Not_Tragedies



Category: Undertale (Video Game)
Genre: Blueberry Tops, Cherryberry - Freeform, Established Relationship, Light Bondage, M/M, Mustardberry, NSFW, Sanscest - Freeform, Smoking, UF!Sans is high as fuck, Underfell, Vaginal Sex, underswap - Freeform
Language: English
Status: Completed
Published: 2016-06-05
Updated: 2016-06-05
Packaged: 2018-07-12 12:35:56
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,184
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7103689
Author URL: https://archiveofourown.org/users/I_Write_Sans_Not_Tragedies/pseuds/I_Write_Sans_Not_Tragedies
Summary: <blockquote class="userstuff">
              <p>Underfell Sans forgets about his date with Underswap Sans and gets high instead. After getting an angry scolding from his brother, UF!Sans and US!Sans have a fun time fucking like rabbits.</p>
            </blockquote>





	Making Purple

**Author's Note:**

> This was a request on tumblr that I don't think was originally NSFW, but hey, who doesn't love some cherryberry smut. It was for Red getting high and Blueberry not being able to handle how cute he is... I took that as "blueberry can't handle how cute Red is so he Fucks The Shit out of him"
> 
> my tumblr is theperfecta, and i do take requests there~

Blueberry knew they were smoking. He huffed about downstairs, cleaning things that were already immaculate, kicking his bare feet on the carpet, glaring up the stairs like the three skeleton’s in Papy’s bedroom could see him.

He couldn’t yell at his brother- he was an adult, who had a job, and could do what he liked. He also couldn't yell at the blue-coated Sans, because he was nice and gave Blueberry hugs sometimes, and his brother was great, too. But he  _ could _ yell at Red, because they were dating, and because he was supposed to be spending time with the other Sans, not smoking weed with his brother.

“This is your house, you know,” Red’s brother said as he sat on the couch, idly watching TV. “If you don’t want them smoking, you could just go up and tell them not to.”

Blueberry exhaled and paused his dusting to look at Papyrus- Boss, as he’d been nicknamed, due to the overwhelming amount of Sans and Papyrus’s in the merged timelines.

“It’s not like they’d listen,” Blueberry said. “Besides! They’re probably too high to take me seriously.”

Papyrus let out a deep, rumbling laugh. “You have a point.”

Sans walked over and threw himself beside the other Papyrus with a sigh. He watched Napstabot for a moment before groaning and throwing his head back.

“We were supposed to go out and do something!” he complained. “That’s the reason he came over in the first place!”

“Go and tell him that,” Boss said.

“I… ugh,” Sans pouted.

Papyrus turned to face him a little more. Sans liked Red’s brother- he was cool and collected, but he was still a Papyrus, so he was passionate and, deep down, a kindhearted guy.

“In all honesty, Sans, he probably forgot,” Papyrus said. “He’s been coping by using drugs and alcohol for a long time, despite my efforts to talk him out of it.”

“Well, if you couldn’t do it, I don’t see how I could,” Blueberry said.

Papyrus smiled. “It’s a different relationship. I’m his brother, I’ve been trying to get him to make the right choices since we were both children. You’re his boyfriend.”

Blueberry mumbled and looked away.

“Just tell him you won’t have sex with him unless he-”

Sans smacked Papyrus’s arm, and the latter cackled out a laugh.

“B-Boss! We don’t do that-”

He put a hand on Blueberry’s shoulder as his laughter subsided, still grinning with his big, sharp fangs. “It’s really not something to be embarrassed about, you’ve been dating for months now. If you wanted it to be a secret, I’d recommend being a little quieter-”

“Oh my god!” 

“Or not leaving your sex toys on the floor-”

“That’s Red! I don’t do that!”

Papyrus cackled while Sans blushed. He grumbled to himself and crossed his arms.

“Really, though,” Boss said after a moment, “it isn’t like it bothers me. I think it’s wonderful that my brother is in a healthy relationship! It’s been a long time since he’s been in a healthy… anything, really.”

Sans was quiet for a moment.

“I think you should go and get him,” Papyrus said.

“Why did Pap have to hang out with Undyne today?” Blueberry whined. “He’d march right up there and yell at all three of them.”

Boss laughed again. “Well, you aren’t wrong. He’s certainly the most straightforward of any of us.”

A bout of laughter came from upstairs, making Sans mumble mild curses under his breath. He didn’t want to be angry, or even jealous, but he was.

Papyrus watched the smaller skeleton with a frown. He leaned back against the couch and crossed his legs.

“He talks about you a lot.”

Sans jumped, pulled out of his quiet wallowing by the statement. Papyrus went on once he’d gotten the little monster’s attention.

“He really enjoys spending time with you. I think he’s told me the story of the time you built snowmen… five times, now? He goes on and on about how impressive yours was, and how you tripped and knocked his over and nearly cried over it.”

“I felt bad…”

Papyrus huffed in amusement. “He still laughs. He cares about you quite a lot, I think.”

“I care about him, too!” Blueberry began, but he groaned and looked away. “He’s just as great as I am, and I tell him that, but he doesn’t believe me. I was just- I was really looking forward to spending time with him today, that’s all…” Sans broke off for a moment. “But… I know he’s having fun up there. I don’t want to ruin… it…”

Sans trailed off as Papyrus stood up and smoothed out his jacket. 

“I’ll be right back.”

“Wh- hey! Don’t yell at him-!”

“I’m not going to yell at him,” Boss said as he began marching towards the stairs. “I’m just going to  _ politely remind  _ him that he was supposed to be spending time with you, not smoking.”

Blueberry opened his mouth to protest, but Papyrus was already halfway up the stairs, and once he made up his mind, there was no stopping him.

Sans waited nervously on the couch. He heard the skeleton rap on the door, and he heard a mumbled response, but they were too far away to make out clearly. A few moments of quiet passed before he heard somebody coming back down the hall at a not-so relaxed pace.

“Blue-” Red began to shout, just as he turned the corner, but he fell down the stairs before he could finish. He’d taken off his jacket and only had on a red shirt and shorts. He picked himself up from his tumble and steadied himself.

“Oh my god! Red, are you okay?” Blueberry worried. He’d already made it halfway to the stairs before Red recovered enough to come hurdling towards Blueberry again.

It was easy to smell the marijuana on him, but he grabbed the smaller Sans in a death-grip and held him.

“I forgot! Oh fuckin- I forgot!”

“Red, it’s o-”

“I forgot!” he babbled again, and he was so high that he was beginning to tear up.

“It’s alright!” Sans said, a tiny bit amused, his relief washing over him. Red hadn’t been ignoring him- he’d just forgotten.

“Noooo it’s not alright!” Red cried, but he pulled back enough to give Sans a sloppy kiss. His breath smelled like smoke, but Blueberry didn’t protest.

“Why don’t you come sit down,” Blue offered, because his counterpart was wobbly on his feet and looked ready to fall. He guided him over to the couch and tried to sit him down, but he threw himself face-first into the cushions and mumbled something unintelligible.

“Red, I can’t understand you with your face in the couch,” Blueberry said. Papyrus had come back down the stairs and was watching in silence.

“I said I’m the worst boyfriend ever!” 

“No you’re not-”

“I forgot! And now I’m high as fuck and I ruined everything,” he whined. He was definitely high as  _ something _ .

“Really, Red, it’s okay.”

He moaned something as though he’d just lost a loved one to disease.

“Red-”

“Nooo. Don’t look at me like that, Blueberry, ‘yer pretty eyes aren’t gonna… aren’t gonna convince me I’m not a piece of shit.”

Sans blushed at the compliment. For a while they just looked at each other, Red’s eyes half-lidded and slow. After a moment had passed he grabbed Blueberry by his bandana and pulled him down to give him another wet kiss.

Papyrus snorted from behind them, and it made Blue draw away in embarrassment, face full-flush. Red stared at him, mesmerized.

“You know,” Papyrus said. Sans jumped, because he hadn’t realized he’d walked over, but Papyrus continued. “You can probably make him do whatever you want right now. He’s very complacent when he’s high.”

“Wh- Papyrus!” he exclaimed, but when he looked he saw Red’s brother giving him a mischievous wink.

“I’ll tell Sans and your brother that there’s more weed at my house. You two have fun.”

“Oh my god!”

“Aww… thanks bro… we’re gonna have  _ sex. _ ”

“Red! You can’t just say that!”

“We’re… not gonna have sex?”

Blueberry’s brain couldn’t move fast enough to process what was happening, but Papyrus slapped him on the shoulder before heading back upstairs.

Red was gazing at Blueberry with heavy, affectionate eyes. Sans was blushing, still trying to recover, but Red pulled him close and hugged him.

“You’re so cute,” he mumbled. Sans didn’t think he could possibly go more blue than he was, but he definitely did. But Red was snuggling into him, and he was warm.

“Red… we’re the same person. You’re cute, too.”

Red barked. “Ha! Yeah, you’re right… but… you’re cuter.” He pressed his forehead against Sans’s. It was awkward, since Sans was sort of crouching beside the couch where Red was lying, but they made do.

“Hey… hey… we can still have sex, right?”

Blueberry laughed, maybe a little higher and more nervous than usual, but Red was adorable. He kissed his boyfriend and gave him a big smile.

“Sure.”

  
  


“Tie me up.”

Blueberry made some kind of noise of surprise, but Red was underneath him, still out of it and high, and his hands were working away at his counterpart’s ribs with desperation.

“Red-”

“Just my hands. Come on- I know you like that shit-”

Blue blushed and regretted giving in and telling Red what he’d found sexy. But Red was laying underneath him, grinding up into his pelvis, already breathing heavily.

“Are you sure you want to?” 

“Y-Yeah- fuck yeah-”

Blueberry didn’t have to move him, he turned around with his wrists behind his back and wiggled them around.

“Tie me up and ride me like a horse.”

Blueberry couldn’t help the laugh that bubbled up in his throat. Red laughed in return and pushed himself up to give Blue’s neck a few sloppy kisses and fondle his ribs.

“You’re so fuckin’ cute- I love you so much-”

Blueberry giggled.

“Don’t laugh- I know I’m high as a goddamn kite.”

“You really are,” he said, but he used his hands to rub Red’s crotch and lick his neck. “If I tie you up, I get to do whatever I want to you.”

Red jerked his hips into Blue’s hands and groaned. 

“Shit, when’d you get so good at bein’ sexy?”

He used his bandana to tie Red’s wrists, putting the makeshift binding tight.

“How’s that?”

“Hot as hell.”

“We need to establish a safe word,” Blueberry said like the responsible boyfriend he was. “How about… uhm…” he looked around his bedroom for a second. “How about Fluffy Bunny?”

“Fluffy Bunny works for me,” Red said, but he was still grinding and trying to get any sort of stimulation he could. His movements were sloppy and untimed, but if Blueberry was being truthful, that just made it hotter.

Red was groaning and mumbling to himself. Blueberry brought his head down and licked his bare ribs, trailing his glowing tongue along the bones and leaving saliva in his wake. He nibbled and sucked on each one in turn, finding the places that made Red moan the loudest, using his hands to hold his shoulders.

“Shit- ohhh fuck, Blue-’

Red cut off with a yelp as his boyfriend made his way to his spine and licked up its exposed length, using his hands to explore his ribs.

“Ha- ha-”

Blue looked up and saw Red watching him in what he could only describe as primal bliss. His eyes were soft and lidded, tongue halfway out of his mouth, drooling, sweating, panting. He bucked his body up into his partner’s motions.

“F-Fuck,” he groaned, averting his eyes. “Fuckin’ hell, you’re good.”

“I learned it from the best,” he said softly as he worked his way over Red’s bones, down to his shorts. He used his hand to press into his crotch, and to his surprise, he found an unexpected wetness between his femurs. He gave Red a questioning look.

“I-It’s- a little hard to suck a dick… if you don’t have lips,” he breathed, flustered. “S’like gettin’ fucked by a cheese grater.”

Blueberry breathed out in amusement, but he was very curious. He’d never experimented with his magic, and he’d never seen a vagina before. He knew the basics, but that wasn’t saying much. He left Red’s shorts on and pressed around the soft magic. God, he was wet.

He helped Red out of his shorts and spread his charge’s legs. He’d formed a red ecto-vagina that was dripping with fluids. Blueberry looked it over for a moment, taking in what it looked like, and how it twitched when he touched Red’s spine. The tied skeleton was bucking his hips with gritted teeth.

“Come on- please-”

A single finger found the strange consistency of the magic, and Red gasped. Sans took that as a good sign and explored his folds, finding the entrance, and what he assumed was a clit. He pressed two fingers to it.

“Ngh-!” Red yelped, rutting upwards into Blueberry’s hands. “F-Fuck- fuck-”

Blueberry moved his fingers over the spot, slowly, drinking in every last noise Red was making. He was letting it all out, the weed in his bones making him less reserved than he usually was. He was panting like a dog, moving his hips up to meet Blue’s movements, legs moving listlessly on the mattress.

He whined when Sans withdrew his fingers. 

He screamed as Sans brought his head down between his femurs and started sucking on his clit.

“Oh god- oh god- oh f-fuck-” he gasped between heated yelps as Sans licked away at his folds, fingers finding their way back to his spine, moving up every once in awhile to lap at Red’s clit. He was barely coherent in his pleading and moaning, head thrown back and back arched and pussy  _ dripping. _

“W-Wait- wait, Blueberry-”

Sans pulled away and wiped his mouth. He opened it to ask what was wrong, still hovering over his boyfriend’s vagina, but Red’s face kept him quiet.

“Fuck me,” he whimpered. Blueberry’s dick twitched.

He didn’t waste a second. He tore his own pants off before replacing his fingers on Red’s entrance. He slipped one inside and Red breathed out a breathy little plea.

He was already relaxed, and it didn’t take long for Sans to comfortably fit three fingers inside. It was slick with fluid.

“C-Come on- fuck me-”

Blueberry would’ve usually been uncomfortable with the way Red was talking, but his boyfriend was tied up underneath him, sweating and panting and gasping, and it was hot as all fuck.

He lined his cock up with Red’s entrance and pressed the tip to the wet magic. He slid himself inside, and Red cried out.

Neither said anything. Sans hadn’t been prepared for how hot and amazing Red’s walls felt around his cock, so he loomed over the other monster and waited for the wave of pleasure to ebb and Red’s cunt to relax. Both were breathing heavily in the dim lighting of the bedroom.

“R-Red,” he breathed, slowly easing himself out.

“I’m good- I’m good- f-fuck. Fuck, Blue.”

He went slow, but even that was enough to make tears of overstimulation prick at the smaller Sans’s eyes. He’d never fucked anyone before. Red was so wet and hot, and he was rolling his hips up around Blueberry’s cock.

“F-Faster- god- please Blueberry-”

“Red- you’re so good-”

Blueberry fell over him, head only inches above Red’s, hands on either side of his head. He gritted his teeth as he rutted into his boyfriend, feeling the pleasure building. He slid his dick out and crammed it back in, and it made Red cry out for more, and that made Blueberry go faster and harder.

“Ha- ha- Red-” Blueberry moaned into the other monster’s ear with his tongue lolling out of his mouth. It felt so fucking good. He couldn’t get enough- he thrusted in and out, the wet, lewd noises spurring him on, Red’s high moans and pleas making him press inside harder.

He felt Red’s walls convulse around him and he squealed.

“I’m g-gonna cum,” Red whined, pushing his hips up into Blueberry’s thrusts. “Fuck- fuck- I-I’m-”

“You’re so good,” Blueberry panted, shoving his dick as hard as he could into Red’s cunt. “You’re so good, Red, you’re so good-”

“F-Fuck- Blue- Blue, Blue, I’m gonna- I’m gonna- oh god-”

Red’s vagina pulsed around Blueberry’s dick and he cried, the sensation too much. His rutting was erratic, untimed, messy. He fucked Red hard and fast as the monster underneath him came and his walls convulsed around Blueberry’s cock.

Blueberry felt the tight coil snap as he came inside of Red. He gasped and whined as his strings of cum were pumped into the skeleton beneath him, and Red groaned at the sensation. Blueberry fucked him through the orgasm, rutting deep inside with a few last desperate thrusts, spending himself inside of Red, until the spurts of cum had ended and he was left shaking, barely able to support himself, staring down into Red’s beautiful face.

He pulled out, and a mixture of his their fluids spilled from Red’s pussy. Blueberry made a face, knowing he’d have to wash the sheets, but Red was still panting beneath him.

He untied the other monster and Red collapsed immediately.

“Fuck. Fuck, Blueberry, that was fucking- that was incredible.”

Sans was trying to catch his breath as he fell onto Red and kissed him. 

“Heh, heheh, oh fuckin’ god,” Red laughed, pulling Blue’s head to his and sloppily kissing him. “You’re so great. You’re- you’re so fuckin’ wonderful.”

“Why… haven’t we done this before?” Blueberry asked, panting, smiling. Red grinned and snuggled into his boyfriend’s collar.

“Tying me up, or fucking me?”

“Both,” Blueberry said, kissing Red’s forehead and running a hand along his ribs. Red was laying underneath him, holding him, and Blueberry had never felt so safe and warm in his life.

“You’re so beautiful,” Red whispered. “You’re so cute, and beautiful, and I love you-”

“You’re so high,” Blueberry said, but he laughed. 

“I’m- I’m not even that high-” Red tried to argue, but he stopped, realizing it was pointless. He laughed and kissed Blueberry in the sloppiest way possible. He peppered his neck with kisses.

“I love you,” he said softly, tenderly. “I mean it.”

“I love you, too,” Blueberry said. 

“Sorry about ditching you,” Red said, and he blushed. “I know it was a dick move…”

“It’s alright… if you hadn’t, you wouldn’t have gotten to feel how  _ my  _ dick moves.”

Red snorted before he broke out into a fit of giggles. “Oh my god! That’s fuckin’ disgusting!”

“Mm… if you say so,” Blueberry said, but he was grinning. “We should make purple more often.”

Red laughed even harder, ribs shaking. He snorted again, and Blueberry found himself laughing, too. He couldn’t get over how cute he was, or how much he loved him, or how much he trusted him. Red cuddled him with vigor, spurred on by the marijuana.

Blueberry would have to thank Red’s brother the next time he saw him.


End file.
